PDF(Pubmed)
Abstract：
Matrix Gla protein (MGP) was originally reported as a physiological suppressor of ectopia calcification and has also been reported to be associated with cancer. However, the relation between the biological functions of MGP and the immune response in colorectal cancer (CRC) remains unclear. Here, we investigated the regulatory role of MGP in the immune microenvironment of CRC. MGP expression in CRC samples was assessed by single-cell RNA sequencing and the Gene Expression Omnibus (GEO) database, and confirmed by quantitative real-time Polymerase Chain Reaction (qRT-PCR) and immunohistochemistry analysis of human CRC samples. The effect of MGP on proliferation and invasion of CRC cells was evaluated by in vitro assays involving MGP knockdown and overexpression. Luciferase reporter assay and chromatin immunoprecipitation (ChIP)-qPCR assay were performed to identify transcriptional regulatory sites of the nuclear factor kappa-B (NF-κB) and programmed cell death ligand 1 (PD-L1). In vivo experiments were performed in mouse model of CRC liver metastasis established via spleen injection. The results revealed that MGP was significantly upregulated in cancer cell clusters from the primary CRC or liver metastases, compared with that in the corresponding paracancerous tissues via single-cell RNA sequencing. MGP enriched intracellular free Ca2+ levels and promoted NF-κB phosphorylation, thereby activated PD-L1 expression to promote CD8+ T cell exhaustion in CRC. The luciferase reporter assay and ChIP-qPCR assay indicated that the transcriptional regulation of NF-κB upregulated PD-L1 expression. In vivo, MGP inhibition significantly decreased the rate of CRC liver metastasis, which was further reduced after combined therapy with αPD1 (anti-PD1). In conclusions, this study revealed that MGP can facilitate CD8+ T cell exhaustion by activating the NF-κB pathway, leading to liver metastasis of CRC. The combination of MGP knockdown and αPD1 can synergistically resist liver metastasis of CRC.
摘要：
基质Gla蛋白（MGP）最初被报道为异位钙化的生理抑制剂，并且也被报道与癌症有关。然而,MGP的生物学功能与结直肠癌（CRC）的免疫反应之间的关系尚不清楚。这里,我们研究了MGP在CRC免疫微环境中的调节作用.通过单细胞RNA测序和基因表达综合（GEO）数据库评估CRC样品中的MGP表达，并通过人CRC样品的定量实时聚合酶链反应(qRT-PCR)和免疫组织化学分析证实。通过涉及MGP敲低和过表达的体外测定来评估MGP对CRC细胞的增殖和侵袭的影响。进行荧光素酶报告基因测定和染色质免疫沉淀（ChIP）-qPCR测定以鉴定核因子κB（NF-κB）和程序性细胞死亡配体1（PD-L1）的转录调节位点。在通过脾注射建立的CRC肝转移小鼠模型中进行体内实验。结果显示，MGP在原发性CRC或肝转移的癌细胞簇中显著上调，通过单细胞RNA测序与相应的癌旁组织进行比较。MGP富集细胞内游离Ca2+水平,促进NF-κB磷酸化,从而激活PD-L1表达以促进CRC中的CD8+T细胞耗尽。荧光素酶报告基因和ChIP-qPCR检测表明NF-κB的转录调控上调PD-L1的表达。在体内,MGP抑制显著降低CRC肝转移率,与αPD1（抗PD1）联合治疗后进一步降低。在结论中，这项研究表明，MGP可以通过激活NF-κB通路促进CD8+T细胞衰竭，导致CRC肝转移。MGP敲除联合αPD1可协同抵抗CRC肝转移。
